The present invention relates to a multiple propagation wave parameter measuring method and apparatus for measuring various parameters of a multiple propagation wave, and a machine-readable recording medium recording a multiple propagation wave parameter measuring program and, more particularly, to a multiple propagation wave parameter measuring method and apparatus for measuring as parameters an arrival direction of a transmission wave radiated from a transmitting means and a change in delay time of the transmission wave from the transmitting means to a receiving means, and a machine-readable recording medium recording a multiple propagation wave parameter measuring program.
FIG. 10 shows the arrangement of a conventional multiple propagation wave parameter measuring apparatus. The multiple propagation wave parameter measuring apparatus shown in FIG. 10 comprises a transmitting device 101 for radiating transmission waves 104 in air and a receiving device 102 for receiving the transmission waves 104 and measuring various parameters.
When the transmission waves 104 are radiated from the transmitting device 101, the receiving device 102 directly receives some of the transmission waves 104. Reflecting members 103 (e.g., buildings) having the function of reflecting an electric wave reflect some of the transmission waves 104, and the receiving device 102 receives the reflected transmission waves. As described above, the transmission waves 104 arrive at the receiving device 102 via various routes. Therefore, the receiving device 102 receives them as a multiple propagation wave.
The receiving device 102 measures the arrival directions of the transmission waves 104 and their delay times from the transmitting device 101 to the receiving device 102 as follows.
An evaluation function is generated to estimate the arrival directions and delay times. This evaluation function is a function of an angle (arrival direction) and time (delay time).
The angular range of 0 to "THgr" and the time range of 0 to t in the evaluation function are calculated at intervals of xcex94"THgr" and xcex94t, respectively. The peaks of the calculation values are found to estimate the arrival directions and delay times.
The delay times of two signals received at different timings are estimated by the above method, and the difference between the delay times is calculated to obtain a change in delay time.
To measure the change in delay time with high precision, a sync signal free from an influence of noise or the like must be used. For this purpose, in the multiple propagation wave parameter measuring apparatus shown in FIG. 10, to supply a sync signal from the transmitting device 101 to the receiving device 102 via a cable 105, the cable 105 connects the transmitting and receiving devices 101 and 102.
In the conventional multiple propagation wave parameter measuring apparatus shown in FIG. 10, a two-dimensional search is performed to estimate the two parameters, i.e., xe2x80x9carrival directionxe2x80x9d and xe2x80x9cchange in delay timexe2x80x9d. This method, however, is time-consuming in signal processing, and a measurement result cannot be immediately obtained.
In the conventional multiple propagation wave parameter measuring apparatus, the cable 105 connects the transmitting and receiving devices 101 and 102. For this reason, the conventional multiple propagation wave parameter measuring apparatus is not suitable for measuring a change in delay time by moving the transmitting device 101 outdoors.
The present invention has been made in consideration of the conventional problems described above, and has as its object to shorten the measurement time for two parameters, i.e., xe2x80x9carrival directionxe2x80x9d and xe2x80x9cchange in delay timexe2x80x9d.
It is another object of the present invention to allow measuring a change in delay time by moving at least one of transmitting and receiving sides.
In order to achieve the above objects of the present invention, there is provided a multiple propagation wave parameter measuring method comprising the steps of radiating transmission waves from transmitting means into an outer space, receiving the transmission waves by receiving means as a multiple propagation wave, measuring arrival directions of the transmission waves on the basis of reception signals output from the receiving means, defining the transmission wave arriving from one direction of the measured arrival directions as a desired wave and the transmission waves arriving from remaining directions as unnecessary waves, calculating a weight with which a reception power ratio of the desired wave to the unnecessary waves becomes maximum, and multiplying the reception signals with the weight to extract the reception signal in which the unnecessary waves are suppressed, and measuring a change in delay time of the desired wave from the transmitting means to the receiving means on the basis of the reception signal in which the unnecessary waves are suppressed.